Known selectors may comprise an inlet aperture, widened out to a greater or lesser degree and protected from the weather to a greater or lesser degree, ending in a passage having a width greater than the width of the document and bounded by an upper face and a lower face. These two faces open into an inlet channel where the document is grasped by a transport means for the document, commonly termed a transport system, and consisting generally of a system of belts or rollers, cylinders, motor and pulleys. The setting in operation of the motor of this system is controlled by a control circuit or "processor", which acquires the necessary data in particular through a system for detecting the document in the aperture; this system comprises for example sensors which detect the presence of paper. The tests for authentication of the document themselves may take place in a second part of the selector, situated after the inlet channel. If the document is not recognized as a genuine note, it is directed towards a rejection outlet, which may be different from the inlet aperture or otherwise, in order to return it to the user, who is assumed to have acted in good faith.
If at the end of these tests the document is recognized as genuine, it is switched towards a box, intermediate or final, depending on the model of automatic machine. In the model with a final box, any note recognized as genuine releases a transaction. In models with an intermediate box ("escrow"), the note is first stored in this intermediate box and its face value is credited. The transaction is released when the selling price is reached. If the user so wishes, he can cancel the request and his documents which have already been introduced are returned to him through the intermediate box. Such a device is described for example in FR-7909576.
It is known to obstruct the passage physically by means of a shutter, situated between the aperture and the inlet channel. The obstruction of the inlet channel is intended to prevent any premature introduction of a further document into the aperture. The routines of acquisition and processing of the signals for detection of a document presented by the user lead to the setting in operation of the transport motor, then to the process of recognition of the document (check or banknote, currency of the note, face value) and to its authentication. These routines take what seems a long time to the user. If the latter then attempts to introduce a second document into the aperture and the inlet channel and the latter is not obstructed, the sensors for detecting the presence of paper then send signals to the processor which disturb the normal functioning of the processor.
FR-7909576 describes a shutter consisting of a smooth plate actuated by an electromagnet which opens it when a presence sensor detects the presentation of a document in the aperture. DE-2323839 describes on the one hand a shutter in the form of a rod sliding in a casing, the rod partially obstructing the passage of the document, and on the other hand a shutter having a width greater than that of the passage of the document, completely obstructing its passage.
In WO 81/01211 (and equivalent publications EP 0028089 and US 4348656), specifically in FIG. 9 thereof, there is disclosed a banknote validator in which an inlet shutter comprises a cylinder carrying a slot therethrough to allow passage of a note in one orientation of the cylinder. However, here is no disclosure of the arrangement by which the shutter is rotated, or of the susceptibility of the shutter to vibration. Separately, in the embodiment of FIG. 11a thereof, an arrangement showing a plurality of fixed teeth is described.
The shutters of the known selectors have the drawback of being sensitive to vibration. If the automatic machine is fixed but subjected to tremors or vibrations, for example on an underground train platform on arrival of a train, or mounted on board a vehicle such as for example a train, these vibrations may open the shutter prematurely and thus permit the introduction of a second document. The second document may then interfere with the processing of the first document and lead to the rejection of genuine notes.
Linear mechanical vibrations fore and aft, up and down or from side to side of the apparatus can thus be converted by the pivotal motion of the inlet shutter (and, for that matter, other shutters or diverters in the apparatus) into substantial pivotal oscillations, depending on the resonances of the shutter.